Pressurized coal scale



INVNTOR ATTORNEYS 4 Sheets-Sheet 1 A, J. s'rocK PREssURIzED com. SCALE z d MWJJEM BY Mey/My sept. 1, 1953v Filed march 27, 1951 Sept. 1, 1953 A. J. STOCK, 2,650,816

PRESSURIZED COAL SCALE Filed March 27, 1951 4 Sheets-Sheet 2 INVENTOR .fr'ahlllod' BY *VM ATTORNEYS SePf- 1, 1953 A. J. sTocK 2,650,816

PRESSURIZED COAL SCALE Filed March 27, 1951 4 Sheets-Sheet 5 L s )iena INVENTOR i? WwW/MM ATTOR NEYS Sept. l, 1953 A. J. s'rocK PREssURIzED com. SCALE Filed March 27, 1951 4 Sheets-Sheet 4 INVENTOR fl'ljurefflod Yz'wmwi/M ATTORNEYS Patented Sept. 1, 1953 UNITED STATES PATENT OFFICE 7 claims.

This invention relates to a pressurized scale and more particularly to a coal scale to be utilized with a pressure or vacuum feed to a furnace in a coal combustion system.

There are many instances where it is necessary and desirable to weigh materials in a hopper under pressure while maintaining the weighing lever assembly for the hopper separate and apart therefrom. This separation is usually an essential feature of arrangements of this nature, and is accomplished by utilizing independent pressure-tight compartments for the weigh hopper and Weigh lever assembly. The separation is considered necessary to preserve the sensitive balance of the weigh lever assembly from distorting or destroying tendencies such as those caused by a deposition or accumulation of foreign materials upon the various levers. Also it serves to prevent the materials contained in the hopper from deleteriously affecting the lever assembly. For example, the materials may have corrosive or oxidizing effects upon the levers of the weigh lever assembly. Additionally, it is often considered desirable to have the lever assembly readily accessible for purposes of adjustment and that such access should be able to be obtained without interference with the materials in the hopper under pressure. As for example, during the weighing of coal the coal dust present is so great that unless the weigh lever assembly is kept separate from the weigh hopper, the coal dust will accumulate on the levers and cause corrosion and will otherwise interfere with the, weighing operation.

The maintenance of separate pressure-tight compartments for the weigh hopper and the weigh lever assembly is extremely necessary for the previously described reasons. Nevertheless, merely maintaining the separation will not of itself result in accurate weighings. This is so in view of the pressure diiferential that exists between the weigh hopper compartment and the Weigh lever assembly compartment inasmuch as the former is under pressure whereas the latter is generally at atmospheric pressure. This pressure difference is generally the result of the manner in which the furnace is operated. For example, use of a cyclone type furnace operating under pressure results in a back pressure throughout the feeding part of the system. Additionally, the only connection between the two compartments usually consists of two rods which are attached to the weigh hopper and which transmit the gross load of the weigh hopper plus the material contained therein to the weigh lever assembly. However, some scale hoppers employ three and sometimes four connecting rods to transmit the gross load. In order to make the joint between the compartments a pressuretight seal, flexible seals in the form of molded rubber bellows are applied to the rods in a conventional manner. This sealing arrangement, however, further enlarges the weigh errors caused by dust accumulation since the unequal pressure caused by the weigh hopper compartment being under pressure results in the molded rubber bellows on the inside of the weigh hopper compartment producing an air piston action which manifests itself as a force acting directly to either raise the Weigh hopper or to thrust the weigh hopper sideways.

Accordingly, this invention provides an arrangement for a pressurized scale whereby the pressure in the weigh hopper compartment is offset by maintaining the weigh lever assembly compartment under air pressure equal to or slightly greater than the pressure in the weigh hopper compartment. This is accomplished generally by providing an air inlet to the weigh lever assembly compartment or control compartment which is connected to a source of air under a pressure greater than any contemplated in the weigh hopper compartment. The air inlet which is normally closed, opens responsive to a large pressure differential between the two compartments in favor of the weigh hopper compartment and admits air into the control compartment until the pressure in the control compartment is slightly greater than the pressure in the weigh hopper compartment. A check valve is established between the two compartments so that if the pressure in the control compartment greatly exceeds that in the weigh hopper compartment, the check valve permits air from the control compartment to leak into the Weigh hopper compartment until the pressure in the control compartment is only slightly greater than the pressure in the Weigh hopper compartment. In this manner large pressure differentials in favor of either compartment are alleviated and accurate weighings can be effected.

It is an object of this invention to provide a pressurized scale which will give accurate weighings.

It is another object of this invention to provide a pressurized coal scale for use with a pressure or vacuum feed to a furnace system which will be more efficient, accurate, and economical than any which have heretofore been available.

Other objects and advantages of the present invention will become apparent from a detailed description of the following specification when taken in conjunction with the drawings in which:

Figure 1 is a view in side elevation showing a pressurized coal scale for use with a feeding system for a pressure or vacuum furnace employing apparatus of the present invention;

Figure 2 is a view in vertical section of Figure 1 taken along line 2--2'; l j

Figure S' isla-1. view. irr. vertical' section of' Figure 2 taken along line 3"-3I l Figure 4 is aview inlvertical section of Figure 2 'taken along line 4'-4.

Figure 5 is a view in horizontal section` of Fig-A ure 2 taken along line 5-5;

Figure 6 is a View in vertical section of Figure 4 taken along line 6 6;

Figure 'i is a view in vertical section through the control compartment showing a modified form of apparatus for maintaining the control compartment pressureslightly greater than the conventional coalya'lvesZflv at; its upper end is joinedlby' known. means; to' a housing 22. It is to '.lce':understood;thatltheV top of the downspout S is normally connected: or. bolted to the bot'- tom: outleti ofi a. coal.' hopper or bunker. housing 2.2lencloses1aaconveyor assembly consisting-j'ofi. al. feed belt 23,. supported on pulleys 26. Skirtplates124 are'. also arranged along the edges of thef conveyor belt 231-. These plates 2d depend from thef'top' ofhousing- 2-2.. Also enclosed in the housing 22 is a weighf. hopper 2li above-described members are.y arranged inside housing 2'2. so` that coal passing through downspoutv 262 will fall ont'othe rear end of belt 23. The coal fallingl off the: forward; end of belt 23 will be receivedintheiweigh hopper. 2l.

The weigh hopper 2 has two pins 235 projecting from opposite sides. rigidity by a' conventional-strut arrangement 33. A' loop'. 29'? attached to oner end of a. shaft 3i) is secured tofeach pin12f8. The other ends of the shafts- Sproject through partitions 3.2" and into compartments` 341 wherev they' are joined to scalebearing loops 31; The shafts 36,' at the points of'proje'ction through: the partitions 32 are encased in.moldedrubberbellows so thatv the.

compartments 3'4 are maintained'. pressure tight with respect to the space' occupied by the weigh hopper 2lland the'conveyor assembly. 'ilhecom-4 partments 34 communicate with anauxiliary housing 35.1 The scale-bearing loops` 3! cooperate with pi'votpins Sii'v rigidly fastened to` weigh leversfSB-to provide a knifefedge` attachment forl the-weigh' hopper 21! with one end of wei'gh levers .36'. A'. knifel edge pivot is provided.

they'will operate as a single unit. Scale-bearingA loops 39 similar to scale-bearing loops 3l and 3l' cooperatev with pivot` pins 52r rigidly fastened` to weigh levers 36 to form af knife edge attachment for a counterweight. 402' with the other ends ofv weigh levers 36a pended between the scale-bearing loops 39.. The weigh hopper 21! is alsof conventionally provided The TheY

Thek pins' 23. are.r given.

The other endsv of the weigh The counterweight isY is suswith a pivoted counterweighted closure member 4l operated in a suitable manner such as by a solenoid to keep the member 4l locked shut. At the proper time the solenoid is de-energized and the weight of the coal in the hopper 2l' causes the member 4| to swing open. When the hopper 21 is empty, the counterweight swings the member 4l shut and the solenoid is energized to effect the locking action. Doors 42 are also formed inA housing 22 to permit. access to the weigh hopper 27 and conveyor assembly.

The auxiliary housing 35 contains a motor 43, the shaft of which is connected to a gear reductor 441.'. rlih'eoutput shaft 45 of the gear reductor 4@ passes through housing 22 and has a gear 46"mou'nted on its end. A gear 4l mounted on al shaft. 4&3V meshes with gear 46. The shaft 48 is joined to the forward pulley 26. As abovedescribed, the motor 43 is mechanically connected to the forward; pulley 26 and thereby power isy supplied to drivethe conveyor belt 23.

The auxiliary housing-I 35 is also provided with.

The auxiliary housing 351 also containsacheck valve 66' communicating with the interiorrv of housing 22 andan air'inlet pipe 61?.

6. Referringi first to Figure 4, it can befseenzthat the check valve 60A is mountedv on the. wall '151` separating auxiliary housing; 35. and.' housing.; 22..

The shaft 45 also projects through this Wall as;

previously described; The: crossbar 33 scalebearing loops 39, andicounterweight 40 attached:

to the ends of levers 3E-1 are heldin. position in auxiliary housing. 3.5.' substantially in compar-tments. 34' pass into auxiliary housing. 'through slots-63.-

The air inlet pipe 6'|- is. situated; iny the top,z wall of auxiliary housingk 35 andv consistsl ofI an coupling 6'4'weld`ed-y intoY a hole in the wall. The. coupling V64' is: internally.I threaded. at: both ends;y

A pipe {55, threaded at its end, is. fitted into. the outsideend'. of coupling 64". This pi'pef 65 is attached. to a supply of air under pressure. This attachment isy not shown.. Ay short pipe 66,

threaded at4 oneend;,is"ttedinto the inside; end of coupling 64. This pipe has: at itsV otherend ak nozzle: 6.1. in the form of1anorin'ce'.-68.-. By. the: arrangement above-described,. airis introduced into'.` auxiliary4 housing 35;'

Referring more particularly now to Figure 6,

the checkvalve; 66x mountedonwall l5: consistsI of-.a circular'wheeli `having a: hubV portionll I, a. rim 72, and spokes 73. The undersurfacef. of therimL 'l2y isundercutand is faced: witha gasket .14

and formsa valve seat. ThelwallS is cutout as indicatedin Figure 6" and the wheel 'I0 is app'liedtol the openingtby means of an intermediate platev 16. A gasket 111 is placedt between the platei 16 andwall5 and also between plate T6' andzwheel 162 Thev assembly including the wheel 'igplate 16, and' gaskets T1 is fastened to wall '151 by means offbolts-i'i8.- A circular member` 80 havingazraised. lipf 8f! and: a shaft 82. centrally mounted nts between thel wheel 16? and plate 161 The lip 8i' formsa valve head andi ts against gasketld The endiofshaft. 82 projects' through hub portion: 'Hi and is screw-threaded andholds a nut' 83.' thereon. compressed spring 8'4` is placed between the nut 83: and the hub portion Ti? to hold' the lip 81` tightly' against gasket T4; A dust shield 85 is bolted to one side of plate 16 so" that the air in auxiliary housing 35Y can pass into housing 22v whenl the pressureof'the air' in the former exceeds that inv the latter by an These two: members` arey shown in detail in Figures i`r and rlhe levers 35 which lie:

amount great enough to onset the iforce exerted by spring 84.

In operation, the apparatus just described, operates to counteract the weighing errors introduced by having the housing 22 at a substantially greater pressure than the auxiliary housing 35. The inlet pipe 6| is connected to a supply of air under pressure. The pressure of the air is at all times greater than the pressure of the air in housing 22. By means of orifice 68, air enters auxiliary housing 35 through pipe 6| at a slow rate. When the pressure in auxiliary housing 35 becomes excessively greater than the pressure in housing 22, the lip 8| will be forced away from gasket 14 by overcoming the force of spring 84 and air will pass from auxiliary housing 35 into housing 22 in the manner previously mentioned. Air will pass into housing 22 until such time as the pressure in auxiliary housing 35 is only slightly greater than that in housing 22, and the diierence is so slight that the force of the spring 84 cannot be overcome. The check valve is arranged to provide a large area upon which air pressure may be exerted. A relatively weak springis preferably utilized as spring 84 so that the pressure diierence between the two housings will be very small. In the event the pressure in the housing 22 increases, this will force lip 8| into tight contact with gasket 14. The pressure in auxiliary housing 35 will gradually build up due to the introduction of air through orice 68 luntil the pressure reaches a value sufficiently high enough to force lip 8| away from gasket 14. Inasmuch as the coal stream flowing through the apparatus is porous, the air which passes into housing 22 will escape through downspout and the hopper or bunker of coal into the atmosphere. Since the interiors of molded rubber bellows are open to compartments 34, the air piston effect upon them will cease when the pressures `of compartments 34 and the weigh hopper compartment are substantially equal.

A modication of this invention is illustrated in Figure '7. In this arrangement an air inlet pipe |20 is introduced into auxiliary housing 35 and terminates within a chamber |2| in a frame |22. Pipe V| 20 is connected to a supply of air under a pressure greater than any which will ever exist in housing 22. The chamber |2| has two outlets |28 which form valve seats. The frame is mounted on the wall 15 between auxiliaryhousing 35 and housing 22 by means of bolts |23 and flange |24. A diaphragm |25 is held between flange |24 and wall 15. A shaft |26having one end secured to the diaphragm |25 is provided with valve heads |21. The shaft |26 projects through chamber |2| and is arranged so that valve heads |21 can seat in outlets |28. The shaft |26 is bearing mounted by means of Vbearing assemblies |29. Thus it can be seen that if the pressure in housing 22 exceeds that inauxiliary housing 35 the diaphragm 25 will move the shaft |26 to open the outlets |28. Air will then pass into auxiliary housing 35 until the pressure therein equals or slightly exceeds the pressure in housing 22. The diaphragm |25- will then be deflected to close outlets |28.

Located directly beneath the previously described apparatus on wall 15 is a check valve for alleviating pressure differences in favor of auxiliary housing 35. A frame |40 is attached about an opening in wall 15 by means of bolts |4| and ilange |42. A gasket |43 is arranged between the flange |42 and wall 15 to eiect a gastight seal. 'I'he inner lip 44 of flange |42 is cut away to form a valve seat. A valve head |45 in the form of a disk having a lip around its' outer edge is mounted for cooperation with the valve seat in the flange |42 by means of a shaft |46 centrally Iixed thereto. The shaft |46 is bearing-mounted in assemblies |41. A pin I 48 is rigidly secured to the shaft |46 and a compressed spring |49 biases the valve head |45 seated in flange |42 by pushing against the pin |48. A dust shield |50 is bolted'to wall 15 and permits air to pass into housing 22 from auxiliary housing 35 when the valve head |45 is not seated. In the manner above described, a pressure difference in favor of auxiliary housing 35` While this invention has been described in spe-- cic embodiments, nevertheless various changes and modifications obvious to one skilled in the;- art are within the spirit, scope, and contempla-- tion of the present invention.

What is claimed is: 1. An apparatus for batch-continuous weighing of aggregate material that comprises an airtight housing divided into an air-tight hopper compartment and an air-tight weighing mechanism compartment, said hopper compartment normally being under other than atmospheric pressure, a weigh hopper positioned in said hopper compartment to receive and discharge said aggregate material as it passes through said compartment, a scale mechanism located in said weighing mechanism compartment, operating connections for said scale mechanism and said hopper extending between said compartments, means responsive to said scale mechanism for operating said hopper, means to supply air to said weighing mechanism compartment under a pressure greater than the pressure in said hopper compartment at a limited rate, and a check valve arranged to permit air to flow from the weighing mechanism compartment to said hopper compartment at a rate sunicient to balance the pressure in the two compartments.

2. An apparatus for batch-continuous weighing of aggregate material that comprises an airtight housing divided into an air-tight hopper compartment and an air-tight weighing mech-' anism compartment, said hopper compartment normally being under other than atmospheric pressure, a weigh hopper positioned in said hopper compartment to receive and discharge said aggregate material as it passes through said compartment, a scale mechanism located in said weighing mechanism compartment, operating connections for said scale mechanism and said hopper extending between said compartments, rubber bellows means sealing said operating connections, means responsive to said scale mechanism for operating said hopper, means to supply air to said weighing mechanism compartment under a pressure greater than the pressure in said hopper compartment, an orifice cooperating with said means to supply air to limit the rate thereof, and a check valve arranged to permit air to ow from said weighing hopper com.- partment to said hopper compartment at a. rate suicient to balance the pressure in the two compartments.

3. An apparatus for batch-continuous weighing The spring |49 will then.`

of'fag'gieglateinaterialthat comprises;their-tight? housingdivided into an a-ir--tieghthopper come partment and` ani airetigiitf weighiifigf.A meoiianismf compartment; said hopper.`I compartment' nore malty' beingfunder other `thanlatmospherieiprese- 52 sure, as weigh hopper.` positioned". in` said* hopperv compartment to=receive=anddiseharge saidgregate-i-material asLit passes ti-i1ougii saidcom'Wl partment;r au scale mechanismi located in'f. said@ weighing.: mechanism: compartment;` operating 10.

afnism compartment? under a pressure greaterrgor than the pressure in said hopperr'compartmerit'fatadimitedorategandzafvcheckzvaive; arran'eed'topermitairzto flowxfrom thefweiehii'igarnech'anissarcomaA laartmentY;tossaidghopiper:compartmeritsatiafrate:A suiicienttto; baianceethe pressure. lin ithe two" come 25 partments.

4. An apparatus for batchecontir'mous- Weighingfoffag-gregatefmaterial that :comprises arrairn tig-ht housing; divided; in'tow an A air-tight hopper compartmentf and an airetight weighirraVA mecha-:m 30 nism compartmenti.. saida hopper corn-partmeritk normailyrbeing'iurider other. than' atmospheric: pressure;A a# weight hopper positioned iri."v sa. if? hopperycompartment-f toiI receives and discharge'- saidsaggregate VYmateriai 1 'as-it passes; through :sai` 3 5 compartment; a iscalefmechanism relocated 'fin isaid Weighing` mechanism: compartment: operaties: connections forxsaid-:scale mechanism and-.asa d; hopperI extendingI betweerrt said; compartmentss,

means`A responsivel to saidiiscale. mechzarrismfA for. 40`

operatinggsaidahopper; aaframe moriiatedzirr vsaid@ Weighing;v mechanism compartment .Y including: chamber, an outiet'tosaid chamberrconstitutin afvalt/ee'seat; a1'diapmagnremoonted:inaawaiii idizL vid-ing said :compartments a# shaft' con-rrectedzlto il 45 said .diaphragm passim-e through said: chamber; ai vaiveehead fmourited Yon ,s fshaf t :adapte d: to t t in Ysaid Va1've-sea t means 1to1 supply to said'i chamber under pressure'lgreater: than the sure; in, said'hopper co-mpafrtriieht; and.; afcheck 50 valve ,arranged-tot, permit airfto fiowf'fromis weghingfmechanismcompartment toosaidhop f per, compartment at ai .sufficient lrate ftorbatancefs theipressi-ires in .thetwo teompartmeiiJ 5.,.An.. .apparatusior.batch-.eonti ing.,of aggregatefmaterial (that f comprises lairs tight i 11o-using@ diivided.: into. air-tighti hoppern compartment and an air-tight rweigh-ihgsmechas n-ism compa-rtmen=t,,-. said hopper n compartment: normally. beings. under: otherv than: atmespirerioe pressure, ,a lweigh :hopper positioned:linfzsaidehope l peri compartment to'. receives4 an'dadischargesaidsi aggregateemateriai as:itipassesithrough"saideome v partira-enti av. scaie mechanismsV located saidfE Weighing:v mechanismi` compartment-I1 operating55 connections: fori said -scaleemechan-ism larid-saidi hopper extend-ing`4r between sai-dcompartments?, means*h responsive f tofsaid" scaler mechanism for`l operatinglsaidhopper; ruboerbeliows means scaliv ing-:said operating connectionaa'irame mounted 70 t in'. said weighirig4 mechanism compartmentin'- chiding aA chamber; an outl'ett to'said" chamber" constitutingfa vai-vefseat; a'daphragln 'mounted in a Wall dividing said compartments* ashaft` connected? to'. saidl diaphragm passingei: throughi said chamber, a valve head mounted ontsaidfshaft; adapted'fto tzih saidzvaivefseat meanszto supply air-to saidichamberunderpressuragreaterrtham thev` pressure:y im;` said; hopper compartment?. andi aiche'clcvaivefarrangeditoifpermit airxtol iiowfiron'frA said Weighing mechanismi compartment toe said? hopper,u compartment?. atlasA suiicientsratepf totv bale anceitheepressure:inithe twocompartments. i

6'.: Anxapparatusefcr batchacontinuous Weighf ing-fof :'agg-regatefmaterial :tha-tl comprisessanffairf-f' tightz housing: dividedi: into; an: airstigfht Hopper*A compartment?. and?. an aim-tight): weighing mechan anism compartimenti, said;` hop-perf compartm'ent'iA Hernia-11@A hei-ng:T under: other? than! atin'espilfier'col pressure, tafcvireigio.ifropper:positionedinl saidhopaper: compartment L to: receives` andi dischargei Saadi aggregates material as it: passese. through; saidi compartmentgaascale mechanismlocatediirr'ssaid Weighing mechanisme compartmenaf. operatingconnections 'z for: said-.2y scale; mechanism armi said-z hopper exterminer bettveenf. said@ compartmeritsa?. means: responsive e tot; said scalemechanism t. fori' operatingzsaid ihopper, moitierbellows4 irreali'siseal-l4 ing; said f operatngz' cormections;4 the interiors ofi` saidrl bellows mearisfzbeingropen to saidl Weighing'i mechanism-compartment;the. exterior ofsaidoeilowsmeansfoeingzexposed tofsaidihoppercompart; vmentgzazframe mountedfinfsaidiweighingrmecl -anisml compartment in'ch'idirrg:v a'a chamberi; arrA outletwo saidiCira-mb'er: constitutingaff-vaifeiseat;Lr a'. diaphragm: mounted iniA af. wail?! dividingI saicl; coiripartiri-ents; a1 shaft fconnected' to:v said@I dia`- pii'ra'gmv.r passing: through. saidr chamb'eua: Valve i head imouvnted onsaidr shaitfadapted Eto` it in said valve-seat;y means to sapply airr-to -said'ichamberf under-pressure greaterrthan'the-pressure insaid hoppericompartmentfi and a xcheek valve arranged tozpermit Lairftof owrfrom isaid' Weigh-ing."naechste` i .charge asg-regatet materialias =it passesl'tirrougli said: compartment, a@ scale mechanism lcated said. second conrpartmentg operating-'fconmece' tions zfor :'saidf i scaie -mechanismf and saidf' mean'sf to'receix'fe and discharge-aggregate material eX-"- tending.: bet-Ween said compartment; means rel sponsivecto said scaie'i mechanism for" operating sai-d: meansf to 2 receive.'c and discl'i'fargeU aggregate m'ateriaLameans -to supply" air-at "ai limit`ed"ratel i totsaidrz'secon'd.'compartment at afpressuretgreatr 0 than-:ethe pressurelsaid "-iirstcompartment andaai check-1 vai-ve i arranged@ to permit'l air`` tof' fiow' from said second icomp'artmentfto' ysaid'irst 'com-"- partmerrtl atfairatessuilicient ltof-balancef-themres lsure inzthe tWoacompartn-rentsi.

ARTHUR'-J STOCK? References-=0ited -in thewrila` orthisspatent:

UNITED YSTATES *PATENTS Number" Name Date 5703299 Ric1'1a1ds.- .0013.: 2?, `.1896 f 112372824 Fastlilg ...SepjtVA 3, 1912"- 2,079,802 Hank .May-11,1937 22136;"445` Kramer NOV.-i15,f.1938- 21385356 Ryan Nov.y .Z9-, .19384J 

